Field of the Invention
The present invention relates to an exhaust structure for combustion apparatus.
Description of the Background Art
A combustion apparatus such as a heating apparatus has a main body that is installed inside of a building such that an exhaust gas is emitted through an exhaust pipe (a B vent) to the outside of the building (for example, see Japanese Patent Laying-Open No. 11-101511). Upon replacing an already-placed combustion apparatus with a new combustion apparatus for certain buildings, for the purpose of reserving the outer appearance of these buildings, an already-placed exhaust pipe cannot be removed.
At such case, the combustion apparatus can be replaced without removing the already-placed exhaust pipe by introducing a new exhaust tube (a flexible exhaust tube) into the already-placed exhaust pipe. However, if the exhaust tube is relatively large in outer diameter, it cannot be installed inside the exhaust pipe. Accordingly, the exhaust tube is needed to be decreased in diameter.
Regarding the above configuration, the exhaust gas emitted out of the top of the exhaust pipe (tip end located outside) or the rain water or the like from the outside may enter into the indoor through a region between an outer circumferential surface of the exhaust tube and an inner circumferential surface of the exhaust pipe. Such problem can be solved by providing an exhaust adapter which is configured to abut against the outer circumferential surface of the exhaust tube and the inner circumferential surface of the exhaust pipe so as to fix both to each other and is configured to separate the abovementioned region and the outdoor.
However, in the above configuration provided with an exhaust adapter, in the case where the exhaust pipe is damaged at a position closer to the combustion apparatus than to a position where the exhaust adapter is installed, such a problem may occur that the exhaust gas that leaks into the abovementioned region from the damaged position of the exhaust pipe will enter into the indoor without being emitted to the outdoor.